Indurstrial robot controlling device

ABSTRACT

Since a release voltage to a brake is applied by a plurality of series-connected contacts and at least one contact is a normally open contact of a relay for controlling a driving power supply of a motor, a control apparatus having a high safety characteristic for an industrial-purpose robot is provided, while even when fusion of a contact happens to occur, the control apparatus can firmly interrupt the application of the release voltage to the brake. Also, the control apparatus for the industrial-purpose robot is provided which need not be equipped with a power supply for releasing the brake by an operator in a manual manner. 
     To this end, in a control apparatus of an industrial-purpose robot ( 11 ) equipped with an electromagnetic type brake ( 23 ) which locks a shaft of a motor, the control apparatus is provided with a first relay contact ( 24 ) which is closed when the electromagnetic type brake ( 23 ) is released, and a second relay contact ( 22 ) which is closed when driving electric power is supplied to the motor; and the first relay contact ( 24 ), the second relay contact ( 22 ), and the electromagnetic type brake ( 23 ) are series-connected to a drive-purpose power supply ( 27 ) of the electromagnetic type brake ( 23 ).

TECHNICAL FIELD

The present invention relates to a control apparatus of anindustrial-purpose robot equipped with an electromagnetic type brakewhich locks a shaft of a motor. More specifically, the present inventionis directed to a control apparatus of an industrial-purpose robot, whichreleases the electromagnetic brake under such a condition that a drivingpower supply of the motor is cut out.

RELATED ART

A motor of an articulated industrial-purpose robot driven by an electroservo motor is controlled to be rotated at a predetermined speed, or tobe stopped at a predetermined position in response to an instructionissued from a control apparatus in order that the robot may be locatedat the predetermined position, or may stand at a predetermined attitude.When the robot is intentionally stopped in response to an instruction ofthe above-explained control apparatus in connection with an interruptionof the driving power supply of the motor, or when the robot isunintentionally stopped due to a certain abnormal event in connectionwith an interruption of the driving power supply of the motor, since theabove-described driving-purpose power supply of the motor is cut out,the motor cannot maintain the predetermined position. Accordingly, anelectromagnetic brake is provided on a motor shaft of theindustrial-purpose robot. When the above-explained electromagnetic brakeis energized, this electromagnetic brake releases constraint of themotor shaft, whereas when the electromagnetic brake is demagnetized,this electromagnetic brake locks the motor shaft. When the motordrive-purpose power supply is cut out, the above-explainedelectromagnetic brake locks the motor shaft in the above-explainedmanner (for instance, Japanese Laid-open Patent Application No.2000-296492).

In the brake apparatus disclosed in Japanese Laid-open PatentApplication No. 2000-296492, a brake releasing-purpose switch contact isclosed so as to apply a power supply voltage to a coil of anelectromagnetic brake which locks a motor shaft, so that locking of themotor shaft is released, while the power supply voltage is produced byrectifying an AC voltage in a half rectifying mode derived from an ACpower supply. In other words, the brake is operated by opening/closing asingle contact.

Also, in such a case that an abnormal event happens to occur while arobot is operated, and thus, the robot is stopped, there is such aproblem that the robot cannot be repaired/adjusted while the robot ismaintained at the stopped attitude thereof, otherwise a trouble mayoccur in operations of other production facilities. As a consequence,the attitude of the robot must be changed by releasing locking of aspecific motor shaft. To this end, a robot control apparatus equippedwith a brake releasing switch is proposed (for instance, JapaneseLaid-open Patent Application No. Hei-8-126990).

Japanese Laid-open Patent Application No. Hei-8-126990 discloses such arobot control apparatus that while a releasing power supply forreleasing a brake by being operated by an operator is provided in therobot control apparatus, both this releasing power supply and a mainpower supply are selectively connected to the brake by employing a mainswitch and an auxiliary switch.

However, in a brake circuit of the industrial-purpose robot described inJapanese Laid-open Patent Application No. 2000-296492, only oneopening/closing contact of the brake circuit is employed. As a result,the following problem may occur. That is, if this open/close contact isfused, then the brake remains released, and thus, the attitude of therobot can be no longer held, so that a serious failure may be conducted.Namely, the robot may collide, or may interfere with a peripheralappliance, or the like.

Also, in the brake apparatus described in Japanese Laid-open PatentApplication No. Hei-8-126990, the brake releasing-purpose power supplymust be provided inside the robot control apparatus. As a result, thereis another problem that the robot control apparatus can be hardly madecompact, and also, the manufacturing cost thereof is increased.

DISCLOSURE OF THE INVENTION

The present invention is made to solve such problems, and therefore, hasan object to provide a control apparatus having a high safetycharacteristic for an industrial-purpose robot, by which while areleasing voltage to a brake is applied by way of a plurality ofseries-connected contacts, even when fusing of the contacts happens tooccur, the application of the releasing voltage to the brake can befirmly interrupted, and also, to provide a control apparatus for anindustrial-purpose robot, which need not be equipped with a power supplyfor releasing the brake by being manually operated by an operator.

To solve the above-described problems, a control apparatus, according tothe present invention, is featured by such a control apparatus of anindustrial-purpose robot equipped with an electromagnetic type brakewhich locks a shaft of a motor, including:

a first relay contact which is closed when the electromagnetic typebrake is released; and

a second relay contact which is closed when driving electric power issupplied to the motor; wherein

the first relay contact, the second relay contact, and theelectromagnetic type brake are series-connected to a drive-purpose powersupply of the electromagnetic type brake. Also, while a signal forclosing the second relay contact is outputted, a signal for closing thefirst relay contact is outputted. Also, the control apparatus furtherincludes:

a control unit for outputting a release signal of the electromagnetictype brake;

manual brake releasing input member for outputting a release signal ofthe electromagnetic type brake by being manually operated by anoperator; and

selecting member for selecting anyone of the release signal outputtedfrom the control unit and the release signal outputted from the manualbrake releasing input member so as to operate the first relay and thesecond relay. Also, the selecting member selects the output from thecontrol unit when the driving power supply of the motor is turned ON,and selects the output from the manual brake releasing input member whenthe driving power supply of the motor is interrupted. Also, the manualbrake releasing input member is provided on a hand held operatingdevice. Further, the manual brake releasing input member corresponds toan external signal.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a structural diagram of a robot system which indicates anembodiment of the present invention.

FIG. 2 is a structural diagram of a brake apparatus of the robot systemwhich represents an embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Now, a description is made of a concrete embodiment of the presentinvention with reference to drawings.

FIG. 1 is a structural diagram of a robot system which indicates anembodiment of the present invention. In this drawing, reference numeral11 shows a robot which should be controlled, and reference numeral 12indicates a robot control apparatus for controlling the robot 11. Therobot control apparatus 12 is provided with a drive apparatus 13, abrake control unit 14, a driving power supply pre-stage controlappliance 16, a control unit 17, and an input/output unit 18. The driveapparatus 13 drives a motor (not shown) of the robot 11. The brakecontrol unit 14 controls a brake of the above-explained motor. Thedriving power supply pre-stage control appliance 16 judges a turn-ONcondition of the driving power supply in response to an emergency stopsignal entered from an external unit, or a control signal entered from apendant 15. The input/output unit 18 inputs and outputs an externalsignal. A brake releasing switch 19 is connected to the brake controlunit 14, and a releasing switch 20 is also connected to the input/outputunit 18.

In order to release the brake by an operation executed by an operator,there are one method for manipulating an operation key of the pendant15, and another method for operating either the brake releasing switch19 or the brake releasing switch 20 (will be explained later) . In sucha case that either the brake releasing switch 19 or the brake releasingswitch 20 is unnecessary, these switches 19 and 20 need not beconnected. Also, in such a case that either the brake releasing switch19 or the brake releasing switch 20 is required, these switches 19 and20 may be alternatively connected.

The pendant 15 corresponds to a hand held operating device used to teachand operate the robot 11, while this pendant 15 is equipped with aplurality of operation keys, a display apparatus, and an enableapparatus. Depression information of the above-described operation keysis transferred to the control unit 17. The enable apparatus correspondsto a dead man switch which is employed so as to secure safety of theoperator in a teaching operation. When the enable apparatus is grippedby the operator in the teaching mode, an enable condition is selected,the driving power supply of the motor is turned ON, and also, a drivesignal is transferred form the driving apparatus 13 to the motor, sothat the motor generates torque, brake releasing electric power issupplied from the brake control unit 14 to the brake so as to releasethis brake, and thus, the robot can be operated by manipulating theoperation key of the pendant 15. When the operator releases gripping ofthe enable apparatus, the enable condition is released, so that thedriving power supply to the motor is interrupted, and since the brakereleasing power supply is cut out, the brake is operable.

FIG. 2 is a structural diagram of a brake apparatus of the robot systemwhich represents an embodiment of the present invention. A brakereleasing operation is carried out in accordance with thebelow-mentioned sequence when either the normal teaching operation or areproducing operation is carried out. Firstly, the control unit 17confirms such a condition that the driving power supply turn-ONavailable condition (emergency stop is not operated etc.) of the motorbased upon a signal derived from the driving power supply pre-stagecontrol appliance 16, and closes a driving power supply control relay21. When the driving power supply control relay 21 is closed, a drivingpower supply relay (electromagnetic contactor) 22 is energized, so thata contact “A” is closed so as to connect a power supply 28 to the driveapparatus 13, and also, a contact “B” is closed. Thereafter, drivecurrents are supplied from the drive apparatus 13 to the respectivemotors (not shown) in response to an instruction issued from the controlunit 17, so that torque is generated in each of the motors. At thistime, in an interlocking switch 25, while a contact “C” is selected, abreak releasing signal flows from the control unit 17 via theinterlocking switch 25 to a brake releasing relay 24, so that the brakereleasing relay 24 is turned ON so as to close the contact thereof. Whenthe brake releasing relay 24 is closed, a current flows from the brakepower apparatus so as to release the brake 23. It should be noted thatother motors are driven and brakes are released in similar sequentialoperations to the above-explained sequential operation.

A method for releasing the brake by entering the operation key of thependant 15 (refer to FIG. 1) is carried out in accordance with thebelow-mentioned sequence. It should also be noted that in order tosecure safety, the brake apparatus must be provided with a doublehold-to-run function known as such a function by which the operatorgrips the enable apparatus when the brake is released (namely, such afunction that enable apparatus is operated only when enable apparatus ismanually operated, and operation of enable apparatus is stopped whenoperator releases enable apparatus).

First, since a predetermined key on the pendant 15 is operated, a brakereleasing master relay 26 is closed. Concretely speaking, an energizingcurrent flows from the control unit 17 via the contact “A” of theinterlocking switch 25 to the brake releasing master relay 26 byoperating the above-described key (it should be noted since robot 11 isunder stopping operation when this key is manipulated, both contact “A”and contact “B” of driving power supply relay 22 are opened). Next, if akey for releasing a brake of a desirable shaft is manipulated, then anenergizing current flows from the control unit 17 via the contact “A” ofthe interlocking switch 25 to the brake releasing relay 24 of thedesirable shaft via the contact “A” of the interlocking switch 25, sothat the brake releasing relay 24 is closed. As a result, since such acircuit is closed which is returned from a brake power supply apparatus27 through the brake releasing relay 24, the brake 23, and the brakereleasing master relay 26 to the brake power supply apparatus 27, abrake releasing current flows through the brake 23, so that the brake 23may be released.

The sequential operation for releasing the brake by operating the brakereleasing switch 20 is the same as the above-described method forreleasing the brake by operating the pendant 15. In other words, if theoperation for closing both the brake releasing master relay 26 and thebrake releasing relay 24 is carried out by operating the brake releasingswitch 20, then currents for closing (energizing) the respective relaysare supplied from the control unit 17.

Next, a description is made of a sequential operation for releasing abrake by operating the brake releasing switch 19. The brake releasingoperation by operating the brake releasing switch 19 is featured by thatthis brake releasing operation is carried out irrespective of thecontrol operation by the control unit 17, namely, corresponds to aso-called “pure manual operation type brake releasing method.”

First, the interlocking switch 25 is manipulated, so that the brakereleasing circuit is connected to a contact “D”. In other words, thebrake releasing relay 24 is separated from the control unit 17, andthen, is connected to the brake releasing switch 19. Next, the brakereleasing switch 19 is manipulated so as to close the brake releasingmaster relay 26. Finally, a switch of the brake releasing switch 19corresponding to a desirable shaft is manipulated, so that the brakereleasing relay 24 of the above-described desirable shaft is closed soas to release the brake 23 of the desirable shaft.

It should also be understand that in the embodiment, the brake releasingswitch 20 is realized as the mechanical switch. Alternatively, the brakereleasing signal may be entered in response to an external signal, forexample, an instruction issued from an upper order control apparatus.

As previously explained, in accordance with the present invention, sincethere are two pieces of the relays for opening and closing the brake,even when one relay of these two relays is fused, the brake power supplycan be cut out by the other relay. As a consequence, there is such anadvantage. That is, such a risk that the brake remains released due tofusion of the relay, and thus, the robot arm drops due to the gravitymay be reduced, so that safety may be improved. Also, since both thebrake power supply apparatus which is normally used, and the brake powersupply which is used in the manual operation are commonly used, anexclusively designed power supply and/or an exclusively designed batteryare no longer employed within the robot control apparatus. As a result,there is another effect that the robot control apparatus can be madecompact.

INDUSTRIAL APPLICABILITY

The present invention is useful as the control apparatus for such anindustrial-purpose robot equipped with the electromagnetic type brakewhich locks the shaft of the motor, more specifically, the presentinvention is useful as the control apparatus for such anindustrial-purpose robot, which releases the electromagnetic brake undersuch a condition that the driving power supply of the motor is cut out.

1. A control apparatus of an industrial-purpose robot equipped with anelectromagnetic type brake which locks a shaft of a motor, comprising: afirst relay contact which is closed when the electromagnetic type brakeis released; a second relay contact which is closed when drivingelectric power is supplied to the motor, wherein the first relaycontact, the second relay contact, and the electromagnetic type brakeare series-connected to a drive-purpose power supply of theelectromagnetic type brake; a control unit for outputting a releasesignal of the electromagnetic type brake; manual brake releasing inputmember for outputting a release signal of the electromagnetic type brakeby being manually operated by an operator; and selecting member forselecting any one of the release signal outputted from the control unitand the release signal outputted from the manual brake releasing inputmember so as to operate the first relay and the second relay.
 2. Thecontrol apparatus of an industrial-purpose robot as claimed in claim 1,wherein the selecting member selects the output from the control unitwhen the driving power supply of the motor is turned ON, and selects theoutput from the manual brake releasing input member when the drivingpower supply of the motor is interrupted.
 3. The control apparatus of anindustrial-purpose robot as claimed in claim 1, wherein the manual brakereleasing input member is provided on a hand held operating device. 4.The control apparatus of an industrial-purpose robot as claimed in claim1, wherein the manual brake releasing input member corresponds to anexternal signal.